Water contamination can be both naturally occurring or caused by man. Naturally-occurring substances like radon, carbon dioxide, and hydrogen sulfide, as well as heavy mineral content, including iron, calcium and manganese, can make water completely unusable or even toxic to some life forms. Reverse osmosis and other membrane filters are often too costly or too complicated for broad-based application. Injection of ozone, air, oxygen and other gases into water streams for disinfection, oxidation and gas stripping have been effectively used.
In order for gas injection to be effective at removing contaminants and/or killing bacteria, the gas must come into physical contact with as much of the water as possible and remain in contact for as long as possible. Typically, the treatment gas is bubbled through the liquid or injected, such as by a venturi. After exposure and contact, the gas is removed prior to use of the liquid.
Prior art systems usually attempt to maximize gas contact by increasing the amount of gas injected into the liquid. This is often insufficient because contact decreases as small bubbles combine into larger bubbles and is effectively terminated once those bubbles reach the top of a mixing vessel or chamber. It is difficult to control contact time other than to make the contact chamber taller, thereby increasing the amount of time it takes for bubbles to gravitate to the top.